My boat came with a mast caddie that has a sticker on it from "Midwest Aquatics". The unit clamps on both the rear cross bar and the mast. Very easy to remove and adjust. I have no idea how old it is (guessing at least 10 years and probably closer to 20 or more), but the caddie seems to be fairly sturdy and everything works great.

You probably now have the last one still in use now that mine broke up. I was looking for an excuse to get rid of the decrepit thing anyway.

I can't see your whole trailer in the picture, but ...... is that where your boat usually sits on the trailer???? The reason I ask is I'm quessing that when being trailered most if not all of your boat forward of the front crossbar is unsupported by the trailer .... if the trailer has rollers you risk damaging the hulls w/ the trailer's front crossbar rollers .... also if the trailer is too short overall, when you turn sharply you can dent your towing vehicle w/ the bow's since the boat is sitting so far forward on the trailer.

On most trailers I've seen, due to their overall design/length/construction the boat's rear crossbar should be just behind the trailer's rear crossbar. This moves the boat (usually) far enough aft so that the wieght of the bows is supported w/ the trailer's front crossbar which should be 12-18" in front of the boat's front crossbar. Now, that means that on most trailers w/ the style of "Rear Mast Support" will pass through the tramp lacings ... or have to extend horizontally rearward 1-2' before turning up, to be effectively behind the boat's rear crossbar. This is were most of the trailers constructed like your's fail .... in this little detail of not extending the rear mast support bracket far enough aft .... leading to boat's being trailered w/o proper support for their bows ... leading to hull damage .....

Please read the thread "H18: Big Project" on this forum that is currently posted .... Tad's boat is a excellent example of the issue I'm talking about ..... and his repairs are EXCELLENT .... please pay close attention to his "cradle fabrication/construction" ....

In the last 25yrs I've trailered my catamarans (if I have to estimate) ... in excess of 150K miles .... my ol' Hosclaw has had its tongue extented (to prevent dents in truck qt'er panel after the first occurence/incident) ... worn out a axle ... and gone through 4 sets of tires ....

.... so I've done a wee' bit of trailering in my youthful days .... before I joined a YC ... and put the stick up only once a season now .....

Oh, my rear mast support???

A "Mast Caddie" .... it clamps to the rear crossbar and clamps around the mast .... and it is no longer made/availible .....